1. Field of the Invention
The present invention relates generally to the examination of the surface reflection of polarized electromagnetic wave radiation, and more particularly to the use of surface reflection of polarized electromagnetic radiation to determine the properties of materials on or near the earth's surface.
2. Description of the Prior Art
Radar imaging, because it can be obtained through cloud cover, at night, over large areas, and with high spacial resolution has been utilized for the remote sensing of agricultural conditions from aircraft or spacecraft. Empirical attempts have been made to correlate soil moisture with signal strength, and to differentiate between fields of different crops by measuring the characteristic radar return at fixed frequencies and at vertically or horizontally oriented linear polarizations. However, no simple and straightforward remote sensing method exists in the prior art for measuring the refractive index of the soil, which is indicative of soil moisture; the refractive index of the vegetation, which is indicative of the water content of the vegetation; and the height of the vegetation.